1. Field of the Invention
The invention relates to a brake device with built-in power generation mechanism and permanent magnetism eddy current, and more particularly to apply on fitness equipment having an integrated power generation function and adjustable braking resistance device.
2. Description of the Related Art
Most fitness equipment includes a flywheel therein to increase the rotational inertia, and the flywheel may be used as a load in order to achieve fitness effects. With reference to FIGS. 1-1 to 1-3, U.S. Pat. No. 5,711,404 discloses a magnetic adjustable loading device with eddy current comprising:
a rotator (not shown) having a flywheel 710 and a metal conductor 720 and a stator 750 having a magnetic plate 751 and a permanent magnet 752 and mounted at an inner periphery of the rotator. With the reference to FIGS. 1-2 and 1-3, a gap d1 between the stator 750 and the flywheel 710 and metal conductor 720 is changed by an adjusting means 770 and a braking means 780 in order to change the magnetic flux density. The braking means 780 has a cable 781 connected to an adjusting element 771 of the adjusting means 770; such that when pulling the cable 781, the adjusting element 771 in a groove 743 moves upward, and a free end of the magnetic plate 751 as shown in FIG. 1-2 is free to move. On the other hand, when loosening the cable 781, a spring 753 allows the free end of the magnetic plate 751 as shown in FIG. 1-3 to return to the original position. The magnetic flux density is changed by the radial displacement of the free end of the magnetic plate 751 in order to achieve the effect of continuous adjustment of load resistance. However, the braking means 780 is operated for adjusting the loading resistance by the user, lacking of automatically adjustment function.
With reference to FIGS. 2-1 and 2-2, U.S. Pat. No. 6,084,325 discloses a brake device with a combination of power-generating and eddy-current magnetic resistance. A rotating wheel A of athletic equipment drives a flywheel 820 to rotate, and a permanent magnet 821 with the flywheel 820 and a stator core 830 together form a magnetic circuit for a coil 831 to generate a current. The current then is changed into direct current through rectification and filtration in order to provide the power to a display & control gauge 890 and a brake core 850 mounted at a side edge of the flywheel 820; such that the brake core 850 forms an eddy-current to produce magnetic resistance. With reference to FIG. 3, U.S. Pat. No. 7,732,961 discloses a combined generator with built-in eddy-current magnetic resistance having a similar applied principle with the above-mentioned U.S. Pat. No. 6,084,325. The only difference is that a brake core 980 disclosed in U.S. Pat. No. 7,732,961 is mounted at an inner periphery of a flywheel 920 instead of being mounted at the side edge of the flywheel 820.
In the aforementioned patents as shown in FIGS. 2-1 to 3, the user imposed the kinetic energy on the athletic equipment to generate the electric power, and electric power is then fed back to produce the magnetic resistance, forming the load of exercise applied force. This kind of structure may achieve an excellent movement effect but may be complex and may cause high manufacturing costs, and thus it is only suitable for installing in larger athletic equipment and athletic equipment with more controlling functions but not suitable for athletic equipment with small resistance and low costs. Moreover, loading adjustment of the aforementioned patents lacks automation. Therefore, there is room for improvement.